How are you confirming this? I have a Samsung KS8000 series TV using the latest 1180.5 firmware. When on an HDMI input, you can hit the "123" button then the "i" for info. It pops-up the graphics input options, and it says UHD 3840x2160 / 60p HDMI UHD Color. On my PS4 Pro, when I am watching a Netflix HDR video it as an "HDR" in a box before UHD. The same is true when playing a PS4 Pro game with HDR enabled.

With the latest Kaby Lake NUC drivers (i have an i5 NUC), there is NO way the input info ever indicates HDR. Doesn't matter if I'm on RGB, limited range, full range, YCBCR, etc. Also doesn't matter if my TV is in "PC" mode or "Blu-Ray Player Mode." I've also tested a ripped HDR Main10 (HEVC) video using MPC, and PowerDVD Ultra 17 (latest build) -- nothing engages the "HDR" logo within the video info tab on my TV.

Again, there's no WDDM 2.2 Intel Graphics drivers that engage the Win10 Creator's Update 10bpc color depth, so I'm not sure that you're in fact getting HDR. It doesn't matter if PowerDVD17 is capable of playing back an HDR Main10 video, if the Intel Graphics Drivers don't utilize WDDM 2.2 (which Intel has responded currently that they're due in early second half of 2017), it doesn't matter what player you use... the HDR content isn't getting passed along from your NUC to the TV.

EDIT: Further evidence of this is the fact that there's no way in Intel's drivers to allow the user to discriminate/toggle between 8bpc color and 10bpc color. Either the signal you're sending is 8bpc color at 4:4:4 OR 10bpc color (which allows for HDR) at 4:2:0. Because the drivers don't have WDDM 2.2 and they don't provide an option to toggle color bit depth, I've confirmed that the signal being sent is only 8bpc color at 4:4:4... which renders HDR impossible.

There's a lot of problems going on with Kaby Lake graphics drivers and it looks like Intel's trying to stay above water. We have whole threads of people who have unstable output flickering and cut-outs on builds past 4664 (and even some on 4664). I think this is priority over them getting HDR working in the latest drivers, so I suspect the "early second half 2017" won't hold (we're already almost in Sep.). Again, nVidia and AMD have had working HDR about 4-5 months ago (since April). I was a first adopter of the first Intel NUC, but I'm sad to say at this point the whole sales pitch of the Kaby Lake NUC being a media user's dream has become a bit of a nightmare. I'm patiently waiting by for a life-line, but I'm not sure how many resource Intel has truly dedicated to their graphics engineering division. It would serve them best to do some workforce poaching from nVidia/AMD to figure out how to get their graphics products and drivers up to par in terms of quality control and features.